Copolycarbonate diol and thermoplastic polyurethane obtained therefrom

ABSTRACT

A copolycarbonate diol comprising:
     (a) recurring units each represented by the following formula (1): 
                 
   (b) recurring units each independently represented by the following formula (2): 
                 
       wherein n is 4, 5 or 6; and   
       (c) terminal hydroxyl groups, wherein the copolycarbonate diol has a number average molecular weight of from 300 to 20,000, and wherein the amount of the recurring units (a) is from 10 to 90% by mole, based on the total molar amount of the recurring units (a) and (b). A thermoplastic polyurethane obtained by copolymerizing the above-mentioned copolycarbonate diol with a polyisocyanate.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/JP02/01900 which has an Internationalfiling date of Mar. 1, 2002, which designated the United States ofAmerica.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a copolycarbonate diol. Moreparticularly, the present invention is concerned with a copolycarbonatediol comprising:

-   (a) recurring units each represented by the following formula (1):-   (b) recurring units each independently represented by the following    formula (2):    -   wherein n is 4, 5 or 6; and-   (c) terminal hydroxyl groups,

wherein the copolycarbonate diol has a number average molecular weightof from 300 to 20,000, and wherein the amount of the recurring units (a)is from 10 to 90% by mole, based on the total molar amount of therecurring units (a) and (b).

The copolycarbonate diol of the present invention is a liquid having lowviscosity. Therefore, the copolycarbonate diol of the present inventionis easy to handle, as compared to the conventional polycarbonate diolswhich are solids or highly viscous liquids. Hence, the copolycarbonatediol of the present invention is advantageous for various uses, such asa raw material for producing a thermoplastic elastomer (such as athermoplastic polyurethane) used for producing various shaped articles(for example, a spandex, which is a polyurethane elastomeric fiber); acomponent for a coating material or an adhesive; and a polymericplasticizer.

The present invention is also concerned with a thermoplasticpolyurethane obtained from the above-mentioned copolycarbonate diol anda polyisocyanate. The thermoplastic polyurethane of the presentinvention exhibits excellent properties with respect to flexibility,heat resistance, low temperature properties, weathering resistance,strength, and molding processability. Therefore, the thermoplasticpolyurethane of the present invention is extremely useful as a materialfor producing various shaped articles, such as automobile parts, partsfor household electric appliances, toys and sundry goods. Especially,the thermoplastic polyurethane of the present invention is useful forproducing shaped articles which are required to have high strength, suchas hoses, sheets and industrial belts; and shaped articles which arerequired to have high flexibility, such as interior and exterior partsfor automobiles (for example, window moles, bumpers, skin parts for aninstrument panel, and grips), spandexes, bands for wristwatches, andshoe soles.

2. Prior Art

A polyurethane and a urethane-, ester- or amide-based thermoplasticelastomer are used in the art. The soft segments of the polyurethane andthermoplastic elastomer are composed of structural units formed from apolyester polyol and/or a polyether polyol, each of which has a hydroxylgroup at each of the molecular terminals thereof (see, for example, U.S.Pat. Nos. 4,362,825 and 4,129,715). A polyester polyol, such as apolyadipate polyol, has poor hydrolysis resistance. Due to the poorhydrolysis resistance, for example, a polyurethane containing, as softsegments, structural units formed from a polyester polyol has adisadvantage in that tackiness and cracks are likely to occur on thesurfaces of shaped articles of the polyurethane within a relativelyshort period of time. Therefore, the use of such a polyurethane isconsiderably limited. On the other hand, a polyurethane containing, assoft segments, structural units formed from a polyether polyol has goodhydrolysis resistance and excellent flexibility. However, thepolyurethane has a disadvantage in that it has poor resistance to lightand oxidative degradation. The disadvantages of these polyurethanes are,respectively, attributed to the presence of ester groups in the polymerchain and the presence of ether groups in the polymer chain.

With respect to the polyester- or polyamide-based thermoplasticelastomer containing, as soft segments, structural units formed from apolyester polyol or a polyether polyol, there has recently been a demandfor improvement in resistance to heat, light, hydrolysis and oil. Inaccordance with the increased demand for such improvement, the samedisadvantages as accompanying the above-mentioned polyurethanes havebeen pointed out with respect also to the thermoplastic elastomer.

A polycarbonate polyol prepared from 1,6-hexanediol is used as a polyolusable for forming soft segments which have excellent resistance tohydrolysis, light, oxidative degradation, heat and the like. Theseresistances are due to the fact that carbonate linkages in the polymerchain exhibit extremely high chemical stability.

However, the polycarbonate polyol prepared from 1,6-hexanediol iscrystalline and hence is a solid at room temperature. Therefore, forproducing a polyurethane from the polycarbonate polyol and apolyisocyanate, it is necessary that the polycarbonate polyol be heatedand melted before effecting a reaction with the polyisocyanate, so thata long period of time is required for producing a polyurethane. In thisrespect, the polycarbonate polyol poses a problem in handling.

As mentioned above, when this polycarbonate polyol is used for formingsoft segments of a polyurethane, the polyurethane has improvedresistance to hydrolysis, light, oxidative degradation and heat.However, the polyurethane has defects in flexibility and low temperatureproperties. Especially, the polyurethane is defective in that itexhibits markedly poor elastic recovery at low temperatures. Due to suchdefects, the polyurethane poses a problem in that it exhibits poorstringiness and hence has poor spinnability. The reason for the poorstringiness is that crystallization is likely to occur in the softsegments of the polyurethane, thus leading to a lowering of theelasticity of the polyurethane. Such easy occurrence of crystallizationin the soft segments results from the high crystallinity of thepolycarbonate polyol prepared from 1,6-hexanediol.

In order to solve these problems, it has been proposed to copolymerize1,6-hexanediol with a polyhydric alcohol having a side chain so as toproduce a copolycarbonate polyol.

For example, in Unexamined Japanese Patent Application Laid-OpenSpecification No. Hei 10-292037, a polycarbonate containing recurringunits derived from 1,6-hexanediol and neopentyl glycol, is disclosed.This polycarbonate is used as a material for a polyurethane, a polyamideelastomer and a polyester elastomer, and as a component for a coatingmaterial and an adhesive.

In Japanese Patent No. 2781104 (corresponding to EP 562 577), apolycarbonate polyol containing recurring units derived from a diolhaving a branched structure and a polyhydric alcohol comprising atetrahydric to hexahydric alcohol, is disclosed. This polycarbonatepolyol is used as a binder for a coating material.

In Unexamined Japanese Patent Application Laid-Open Specification No.Hei 2-49025 (corresponding to EP 343 572), a polycarbonate diolcontaining recurring units derived from a C₃-C₂₀ polyhydric alcoholhaving a side chain and 1,6-hexanediol, is disclosed. This polycarbonatediol is used as a material for producing a polyurethane.

In Japanese Patent No. 2506713, a polycarbonate diol containingrecurring units derived from 2-methyl-1,8-octanediol or recurring unitsderived from a diol comprised mainly of 2-methyl-1,8-octanediol and1,9-nonanediol, is disclosed. This polycarbonate diol is used as amaterial for producing a polyurethane, a polyamide elastomer and apolyester elastomer, and is used in the fields of a coating material andan adhesive.

WO 98/27133 discloses a polycarbonate polyol containing recurring unitsderived from a diol having a side chain which contains two lower alkylgroups, and a polyurethane produced using, as a soft segment, thispolycarbonate polyol.

These polycarbonate polyols have a side chain, and, therefore, theelastomers (such as polyurethanes) produced using, as a soft segment,these polycarbonate polyols, have a side chain, i.e., they have abranched structure. Due to such branched structure, the polycarbonatepolyols have a problem in that the elastomers produced using thesepolycarbonate polyols exhibit poor mechanical properties, as compared tothose of elastomers which have no side chains.

When a thermoplastic elastomer is produced using, as a soft segment, apolycarbonate polyol prepared from a bulky polyhydric alcohol (e.g.,neopentyl glycol) which contains a quaternary carbon atom having twoside chains bonded thereto, the strength of the thermoplastic elastomeris lowered depending on the content of the recurring units derived fromthe above-mentioned bulky polyhydric alcohol.

When a thermoplastic elastomer is produced using, as a soft segment, apolycarbonate polyol prepared from a polyhydric alcohol which contains atertiary carbon atom having one side chain bonded thereto, there is aproblem in that the heat aging resistance of the thermoplastic elastomeris lowered. The reason for occurrence of such a low heat agingresistance of the thermoplastic elastomer is that the hydrogen atomwhich is bonded to the tertiary carbon atom having one side chain islikely to become a radical so as to be easily eliminated from thetertiary carbon atom, as compared to a hydrogen atom which is bonded toa secondary carbon atom having no side chains.

As another measure for lowering the crystallinity of a polycarbonatepolyol prepared from 1,6-hexanediol, it has been proposed that1,6-hexanediol is copolymerized with a diol having no side chains so asto produce a copolycarbonate diol.

For example, Examined Japanese Patent Application Publication No. Hei5-29648 (corresponding to EP 302 712 and U.S. Pat. Nos. 4,855,377 and5,070,173) discloses an aliphatic copolycarbonate diol produced using1,5-pentanediol and 1,6-hexanediol.

Generally, even when a homopolymer which is obtained by homopolymerizinga monomer is crystalline, a copolymer which is obtained bycopolymerizing the monomer with an appropriate comonomer has lowcrystallinity, as compared with the homopolymer; the reason for this isthat the structural regularity of the copolymer is disordered by thecomonomer units. In the case of a copolycarbonate polyol containing1,6-hexanediol units, when the comonomer diol units are, for example,those derived from a diol which contains an odd number of methylenegroups, such as 1,5-pentanediol, the structural regularity of thecopolycarbonate polyol is likely to be greatly disordered, as comparedto the case where the comonomer diol units are those derived from a diolwhich contains an even number of methylene groups.

However, this copolycarbonate diol is a solid or a viscous liquid, sothat the handling properties of the copolycarbonate diol areunsatisfactory, depending on the use thereof.

In recent years, a thermoplastic polyurethane which is produced using,as a soft segment, a copolycarbonate diol prepared from a mixture of1,6-hexanediol and 1,4-butanediol or 1,5-pentanediol is attractingattention because of its great advantages. (The above-mentionedcopolycarbonate diol is disclosed in Examined Japanese PatentApplication Publication No. Hei 5-029648 (which is mentioned above) andJapanese Patent No. 3128275; and the above-mentioned thermoplasticpolyurethane is disclosed in Unexamined Japanese Patent ApplicationLaid-Open Specification No. Hei 5-51428 and Japanese Patent No. 1985394(corresponding to EP 302 712 and U.S. Pat. Nos. 4,855,377 and5,070,173).) Specifically, such thermoplastic polyurethane hasadvantages in that it has remarkably excellent properties with respectto flexibility and low temperature properties, as well as the sameexcellent properties as mentioned above and as achieved by using, as asoft segment, a polycarbonate diol prepared from 1,6-hexanediol, i.e.,excellent resistance to hydrolysis, light, oxidative degradation andheat.

However, in the course of the studies of the present inventors, it wasfound that the thermoplastic polyurethane produced using, as a softsegment, the above-mentioned copolycarbonate diol has a problem in thatthe flexibility is still unsatisfactory and hence the use of thethermoplastic polyurethane is limited.

With respect to polycarbonate diols other than those mentioned above,there are documents which refer to the use of a polycarbonate diolprepared from 1,3-propanediol.

For example, in WO 01/72867, there is disclosed a thermoplasticpolyurethane produced using, as a soft segment, a polycarbonate diol inwhich the diol units are composed only of 1,3-propanediol units.However, this thermoplastic polyurethane is hard and exhibits highmodulus (that is, the elongation of the thermoplastic polyurethane isunsatisfactory), rendering it difficult to use the thermoplasticpolyurethane in the same application fields as those of the ordinaryelastomers. The reason for this has not yet been completely elucidated;however, the reason is presumed to be as follows.

In the above-mentioned polycarbonate diol, each recurring unit has onlythree methylene groups (derived from 1,3-propanediol), so that the ratioof the carbonate linkages in the polycarbonate diol molecule is high.The flexibility of such polycarbonate diol molecule is lowered, andhence, the thermoplastic polyurethane produced using such polycarbonatediol exhibits low elasticity.

Examined Japanese Patent Application Publication No. Hei 8-32777discloses a process for rapidly producing a polycarbonate diol,comprising subjecting a mixture of a dialkyl carbonate and a hydroxycompound or a mixture of a diaryl carbonate and a hydroxy compound to atransesterification reaction in the presence of a titanium compound or atin compound. This process is intended to rapidly produce a high qualitypolycarbonate diol which is less likely to suffer discoloration.

In this prior art document, as examples of hydroxy compounds,1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol aredescribed. However, in this prior art document, no polycarbonate diol isactually produced using 1,3-propanediol. Further, no polyurethane isproduced using a polycarbonate diol, and no evaluation is made withrespect to the properties of a polyurethane.

Unexamined Japanese Patent Application Laid-Open Specification No. Hei4-239024 discloses the following process. First, a reaction mixturewhich contains a low molecular weight polycarbonate diol is produced. Adiaryl carbonate is added to the reaction mixture produced, and areaction is performed while removing a by-produced alcohol, therebyproducing a high molecular weight polycarbonate diol. This process isintended to produce a polycarbonate diol using a monomer in a smallamount.

In this prior art document, as examples of diols which are usable as amaterial for producing the polycarbonate diol, 1,3-propanediol,1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol are described.However, in this prior art document, no polycarbonate diol is producedusing 1,3-propanediol. Further, no polyurethane is produced using apolycarbonate diol, and naturally, any evaluation is not made withrespect to the properties of a polyurethane.

As apparent from the foregoing, conventionally, there has not yet beenobtained a polycarbonate diol which is suitable as a material forproducing a thermoplastic polyurethane which is advantageous not only inthat it exhibits excellent resistance to hydrolysis, light, oxidativedegradation and heat, but also in that it exhibits excellent propertieswith respect to flexibility and low temperature properties.

SUMMARY OF THE INVENTION

In this situation, the present inventors have made extensive andintensive studies with a view toward developing a thermoplasticpolyurethane which is advantageous not only in that it exhibitsexcellent resistance to hydrolysis, light, oxidative degradation andheat, but also in that it exhibits excellent flexibility comparable tothat of a polyether-based thermoplastic polyurethane, and exhibitsexcellent low temperature properties, especially excellent elasticrecovery at low temperatures, and with a view toward developing apolycarbonate diol which is suitable as a material for producing thethermoplastic polyurethane and which is easy to handle. As a result ofthese studies, it has unexpectedly been found that a copolycarbonatediol which is obtained by copolymerizing at least one diol selected fromthe group consisting of 1,4-butanediol, 1,5-pentanediol and1,6-hexanediol with 1,3-propanediol, is advantageous not only in that itexhibits excellent handling properties, but also in that a thermoplasticpolyurethane which is obtained by copolymerizing this copolycarbonatediol with a polyisocyanate exhibits excellent properties with respect toflexibility and low temperature properties, as well as excellentresistance to hydrolysis, light, oxidative degradation and heat.

The above-mentioned copolycarbonate diol comprises

-   (a) recurring units each represented by the following formula (1):-   (b) recurring units each independently represented by the following    formula (2):    -   wherein n is 4, 5 or 6; and-   (c) terminal hydroxyl groups.

The present invention has been completed on the basis of these novelfindings.

Accordingly, it is an object of the present invention to provide acopolycarbonate diol which exhibits excellent handling properties and issuitable as a material for producing a thermoplastic polyurethane whichexhibits excellent properties with respect to flexibility and lowtemperature properties, as well as excellent resistance to hydrolysis,light, oxidative degradation and heat.

It is another object of the present invention to provide a thermoplasticpolyurethane exhibiting excellent properties, which is obtained bycopolymerizing the above-mentioned copolycarbonate diol with apolyisocyanate.

The foregoing and other objects, features and advantages of the presentinvention will be apparent to those skilled in the art from thefollowing detailed description and appended claims.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, there is provided a copolycarbonatediol comprising:

-   (a) recurring units each represented by the following formula (1):-   (b) recurring units each independently represented by the following    formula (2):    -   wherein n is 4, 5 or 6; and-   (c) terminal hydroxyl groups,

wherein the copolycarbonate diol has a number average molecular weightof from 300 to 20,000, and wherein the amount of the recurring units (a)is from 10 to 90% by mole, based on the total molar amount of therecurring units (a) and (b).

For easy understanding of the present invention, the essential featuresand various preferred embodiments of the present invention areenumerated below.

1. A copolycarbonate diol comprising:

-   (a) recurring units each represented by the following formula (1):-   (b) recurring units each independently represented by the following    formula (2):    -   wherein n is 4, 5 or 6; and-   (c) terminal hydroxyl groups,

wherein the copolycarbonate diol has a number average molecular weightof from 300 to 20,000, and wherein the amount of the recurring units (a)is from 10 to 90% by mole, based on the total molar amount of therecurring units (a) and (b).

2. The copolycarbonate diol according to item 1 above, which has anumber average molecular weight of from 500 to 10,000.

3. The copolycarbonate diol according to item 1 or 2 above, wherein theamount of the recurring units (a) is from 20 to 80% by mole, based onthe total molar amount of the recurring units (a) and (b).

4. A thermoplastic polyurethane obtained by copolymerizing thecopolycarbonate diol of any one of items 1 to 3 above with apolyisocyanate.

Hereinbelow, the present invention will be described in detail.

The copolycarbonate diol of the present invention comprises:

-   (a) recurring units each represented by the following formula (1):-   (b) recurring units each independently represented by the following    formula (2):    -   wherein n is 4, 5 or 6; and-   (c) terminal hydroxyl groups.    Due to such structure, the structural regularity of the    copolycarbonate diol of the present invention is low, as compared to    that of a polycarbonate diol which is a homopolymer.

The recurring unit (a) contains only three methylene groups, i.e., asmall odd number of methylene groups. A recurring unit containing asmall odd number of methylene groups tends to be more effective fordisordering the structural regularity of a copolycarbonate diol thanother recurring units. Therefore, by virtue of the use of the recurringunit (a), the crystallinity of the copolycarbonate diol is lowered, sothat the copolycarbonate diol is an amorphous polymer such that acrystallization temperature and a melting temperature are not observedin analyses by differential scanning calorimetry (DSC). As a result, theviscosity of the copolycarbonate diol is lowered and the copolycarbonatediol is easy to handle. In addition, a thermoplastic polyurethaneobtained using the copolycarbonate diol exhibits improved flexibility.Further, a thermoplastic elastomer (especially a thermoplasticpolyurethane) produced using the amorphous copolycarbonate diol exhibitsexcellent stringiness.

In the copolycarbonate diol of the present invention, the amount of therecurring units (a) is from 10 to 90% by mole, preferably from 20 to 80%by mole, more preferably from 30 to 70% by mole, based on the totalmolar amount of the recurring units (a) and (b).

Such copolycarbonate diol is generally a viscous liquid at roomtemperature, but the viscosity of the copolycarbonate diol is lower thanthose of the conventional polycarbonate diols. Therefore, when thecopolycarbonate diol of the present invention is used as a material forproducing a thermoplastic elastomer (such as a thermoplasticpolyurethane) or as a component for a coating material or an adhesive,the copolycarbonate diol is easy to handle.

It is especially preferred that a thermoplastic polyurethane is producedusing a copolycarbonate diol of the present invention wherein the amountof the recurring units (a) is from 30 to 70% by mole, based on the totalmolar amount of the recurring units (a) and (b). A thermoplasticpolyurethane produced using such copolycarbonate diol exhibits excellentproperties with respect not only to flexibility and modulus (that is,the modulus is low), but also to elongation and impact resilience. Thatis, such thermoplastic polyurethane exhibits extremely advantageousproperties which are similar to those of a vulcanized rubber.

The number average molecular weight of the copolycarbonate diol of thepresent invention is from 300 to 20,000, preferably from 500 to 10,000,more preferably from 800 to 3,000.

When the number average molecular weight of the copolycarbonate diol isless than 300, the flexibility and low temperature properties of thethermoplastic polyurethane produced using the copolycarbonate diol tendsto be unsatisfactory. On the other hand, when the number averagemolecular weight of the copolycarbonate diol is more than 20,000, themolding processability of the thermoplastic polyurethane produced usingthe copolycarbonate diol is lowered.

In the present invention, the number average molecular weight of thecopolycarbonate diol is determined from the hydroxyl value of thecopolycarbonate diol, by the following method. More specifically stated,first, the hydroxyl (OH) value of the copolycarbonate diol is determinedby the neutralization titration method (JIS K 0070-1992), which usesacetic anhydrate, pyridine and an ethanol solution of potassiumhydroxide. The number average molecular weight (Mn) is calculated fromthe OH value in accordance with the following formula:Mn=56.1×2×1,000÷OH value

It is preferred that substantially all terminal groups of thecopolycarbonate diol of the present invention are hydroxyl groups. Theterminal groups of the copolycarbonate diol can be determined bymeasuring the acid value of the copolycarbonate diol or analyzing thecopolycarbonate diol by ¹³C-NMR (¹³C-nuclear magnetic resonance)spectroscopy. The acid value of a substance is the amount (mg) ofpotassium hydroxide (KOH) required for neutralizing the acidic groups in1 g of the substance. When the acid value of the copolycarbonate diol is0.01 or less, the copolycarbonate diol contains substantially no acidgroups and, therefore, it is confirmed that substantially all terminalgroups of the copolycarbonate diol are hydroxyl groups.

Hereinbelow, an explanation is made with respect to the process forproducing the copolycarbonate diol of the present invention.

The copolycarbonate diol of the present invention can be obtained bysubjecting to a polymerization reaction the following components:

-   (I) 1,3-propanediol;-   (II) at least one diol selected from the group consisting of    1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol; and-   (III) a carbonate compound.

The amount of 1,3-propanediol (hereinafter, frequently referred to asthe “diol (I)”) is from 10 to 90% by mole, preferably from 20 to 80% bymole, more preferably from 30 to 70% by mole, based on the total molaramount of the diols (I) and (II).

Examples of carbonate compounds (III) above include dialkyl carbonates,such as dimethyl carbonate, diethyl carbonate and dibutyl carbonate;alkylene carbonates, such as ethylene carbonate, 1,2-propylene carbonateand trimethylene carbonate; and diaryl carbonates, such as diphenylcarbonate. Among these, alkylene carbonates are preferred, since whenalkylene carbonates are used for producing the copolycarbonate diol ofthe present invention, a copolycarbonate diol in which substantially allterminal groups are hydroxyl groups can be easily obtained. Suchcopolycarbonate diol is especially advantageous as a material forproducing a thermoplastic polyurethane.

Among alkylene carbonates, ethylene carbonate is preferred, since theuse of ethylene carbonate provides the following advantage.

In the above-mentioned polymerization reaction, there is by-produced acompound containing a hydroxyl group, which is derived from thecarbonate compound (III) (hereinafter, this by-product is referred to asa “hydroxyl group-containing by-product”). When ethylene-carbonate isused as the carbonate compound (III), the hydroxyl group-containingby-product is ethylene glycol. Ethylene glycol has a relatively lowboiling point and hence can be easily removed from the reaction system.

With respect to the amount of the carbonate compound (III), there is noparticular limitation. However, in general, the molar ratio of thecarbonate compound (III) to the total molar amount of the diols (I) and(II) is from 20:1 to 1:20.

It is preferred that the copolycarbonate diol of the present inventionis produced using only the above-mentioned components (I) to (III). Thereason for this preference is that there can be obtained advantages inthat the polymerization reaction is almost not limited by the meltingpoints and boiling points of the diols (I) and (II), and that athermoplastic polyurethane produced using the obtained copolycarbonatediol exhibits especially improved flexibility. However, if desired, apolyhydric alcohol other than the diols (I) and (II) can be used incombination with the diols (I) and (II) as long as the effects of thepresent invention are not adversely affected.

Examples of polyhydric alcohols include linear diols, such as1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol,1,11-undecanediol and 1,12-dodecanediol; branched diols, such asneopentyl glycol, 3-methylpentane-1,5-diol, 2-ethyl-1,6-hexanediol,2-methyl-1,3-propanediol and 2-methyl-1,8-octanediol; cyclic diols, suchas 1,3-cyclohexanediol, 1,4-cyclohexanediol,2,2-bis(4-hydroxycyclohexyl)-propane and 1,4-cyclohexanedimethanol; andalcohols containing three or more hydroxyl groups, such astrimethy-lolethane, trimethylolpropane, hexanetriol and pentaerythritol.

The suitable amount of the polyhydric alcohol varies depending on thetype of the polyhydric alcohol.

When a linear diol is used as the polyhydric alcohol, the amount of thelinear diol is generally 20% by mole or less, preferably 10% by mole orless, based on the total molar amount of the diols (I) and (II).

When a branched diol and/or a cyclic diol is used as the polyhydricalcohol, it is preferred that the amount of the polyhydric alcohol isless than in the case where a linear diol is used as the polyhydricalcohol. Specifically, the amount of a branched diol and/or a cyclicdiol is generally 15% by mole or less, preferably 5% by mole or less,based on the total molar amount of the diols (I) and (II).

The reason why, when a branched diol and/or a cyclic diol is used as thepolyhydric alcohol, it is preferred that the amount of the polyhydricalcohol is less than in the case where a linear diol is used as thepolyhydric alcohol, is as follows. When a branched diol and/or a cyclicdiol is used for producing a copolycarbonate diol, the strength and heataging resistance of a thermoplastic polyurethane produced using thecopolycarbonate diol tend to be lower than those of a thermoplasticpolyurethane produced using a copolycarbonate diol produced by a processusing a linear diol as the polyhydric alcohol.

When an alcohol containing three or more hydroxyl groups is used as thepolyhydric alcohol, a reaction product obtained by the polymerizationreaction performed for producing the copolycarbonate diol of the presentinvention, is a copolycarbonate polyol containing three or more hydroxylgroups. In the present invention, such copolycarbonate polyol is alsoregarded as the copolycarbonate diol of the present invention.

In the case where an alcohol containing three or more hydroxyl groups isused as the polyhydric alcohol, the amount of the polyhydric alcohol isgenerally 10% by mole or less, preferably 5% by mole or less, based onthe total molar amount of the diols (I) and (II). When the amount of thepolyhydric alcohol is too large, too large an amount of crosslinkagesare introduced into a polyurethane produced using the copolycarbonatediol, thus leading to a lowering of the thermoplasticity of thepolyurethane.

With respect to the method for performing the polymerization reaction,there is no particular limitation, and the polymerization reaction canbe performed by using conventional methods, such as the various methodsdescribed in “Polymer Reviews”, Vol. 9, pp. 9-20, written by H. Schnell(published by Interscience Publishers, U.S.A., 1964), and the methoddescribed in the above-mentioned Examined Japanese Patent ApplicationPublication No. Hei 5-29648.

Hereinbelow, an explanation is made of an example of a method forproducing the copolycarbonate diol of the present invention, whichcomprises the following two steps:

(1) performing a polymerization reaction of the above-mentioned rawmaterials (I) to (III) and optionally the polyhydric alcohol, whileremoving the hydroxyl group-containing by-product from the reactionsystem, to thereby obtain a copolycarbonate prepolymer; and

(2) performing a self-condensation of the above-obtained copolycarbonateprepolymer,

to thereby obtain the copolycarbonate diol of the present invention.

First, an explanation is made of the step (1).

In the step (1), the diol (I) (1,3-propanediol), the diol (II) (at leastone diol selected from the group consisting of 1,4-butanediol,1,5-pentanediol and 1,6-hexanediol), the carbonate compound (III) andoptionally the polyhydric alcohol are mixed together, and the resultantmixture is subjected to a polymerization reaction, to thereby obtain acopolycarbonate prepolymer.

Hereinbelow, an explanation is made taking as an example the case whereonly the diols (I) and (II) and the carbonate compound (III) are used asthe raw materials. With respect to the case where the polyhydric alcoholis used as an optional raw material, the polyhydric alcohol isconsidered to show substantially the same behavior as that of the diol(II), in the polymerization reaction.

The main reactions involved in the polymerization reaction are theaddition reaction, namely, the reaction of addition of the diol (I) or(II) to the carbonate compound (III), and the transesterificationreaction between the reaction product of the addition reaction and thediol (I) or (II). As the transesterification reaction proceeds, thehydroxyl group-containing by-product is eliminated from the carbonatecompound (III). Since the transesterification reaction is an equilibriumreaction, when the hydroxyl group-containing by-product accumulates inthe reaction system, the polymerization does not satisfactorily advance.Therefore, it is preferred that the polymerization reaction is performedwhile removing the hydroxyl group-containing by-product from thereaction system.

More specifically, it is preferred that the polymerization reaction ofthe step (1) is performed in the following manner: a vapor containingthe hydroxyl group-containing by-product which is produced during thepolymerization reaction, is generated, and the thus generated vapor iscondensed to obtain a condensate, and at least a part of the thusobtained condensate is removed from the reaction system. Forfacilitating the generation of the vapor, it is preferred that thepolymerization reaction is performed under reduced pressure.

In this instance, for increasing the efficiency of the removal of thehydroxyl group-containing by-product, a method may be adopted in whichan inert gas (such as nitrogen, argon, helium, carbon dioxide and alower hydrocarbon gas) which does not have an adverse effect on thepolymerization reaction, is introduced into the reaction system so thatthe hydroxyl group-containing by-product is removed in a form entrainedby the inert gas.

For suppressing the distillation of the diols (I), (II) and thecarbonate compound (III), and for efficiently removing the hydroxylgroup-containing by-product from the reaction system, it is preferredthat the polymerization reaction is performed in a reactor equipped witha fractionating column. When using a fractionating column, theseparating capability thereof is important. Hence, a fractionatingcolumn is used which generally has a number of theoretical plates of 5or more, preferably 7 or more.

A fractionating column is used generally in such a form as equipped, atits top, with an appropriate reflux condenser. The reflux condenser isused for condensing the vapor ascending inside of the fractionatingcolumn, to form a condensate, and for causing at least a part of thecondensate to flow down inside of the fractioning column, back to thereactor. Use of such a fractionating column is advantageous in that thevapor containing the hydroxyl group-containing by-product (which ascendsinside of the fractionating column) and the condensate (which flows downinside of the fractionating column) contact each other in a counterflow, thereby causing the hydroxyl group-containing by-product in thecondensate to move into the vapor, and also causing the diols (I) and(II) and the carbonate compound (III) in the vapor to move into thecondensate, to thereby facilitate the efficient removal of the hydroxylgroup-containing by-product from the reaction system.

In the process for producing the copolycarbonate diol of the presentinvention, it is preferred that the polymerization reaction is performedby using the reactor as mentioned above, while generating a vaporcontaining the hydroxyl group-containing by-product, and the generatedvapor is condensed into a condensate by means of a reflux condenser,followed by removal of a part of the obtained condensate as a distillatefrom the reaction system while causing the remainder of the condensateto flow down inside of the fractioning column, back to the reactor.

By setting in an appropriate range the volume ratio of the condensatereturned to the reaction vessel, relative to the condensate removed as adistillate from the reaction system (i.e., the reflux ratio), advantagescan be obtained in that the distillation of the diols (I), (II) and thecarbonate compound (III) can be suppressed, thereby increasing theefficiency of the reaction. With respect to the appropriate range ofreflux ratio, although it varies depending on the performance of thefractionating column, the reflux ratio is generally in the range of from3 to 10, preferably from 3 to 7.

In addition, for efficiently performing the polymerization reaction, itis important to appropriately control the amount of the vapor(containing the hydroxyl group-containing by-product) which ascendsinside of the fractionating column per unit time (i.e., it is importantto appropriately control the so-called “throughput”). When thethroughput is too small, the rate of removal of the hydroxylgroup-containing by-product becomes low and hence the reaction timebecomes long. On the other hand, when the throughput is too large, theefficiency of the reaction is decreased, due to, e.g., the distillationof the diols (I) and (II). Therefore, it is preferred that thethroughput is as great as possible, as long as the efficiency of thereaction is not decreased.

The control of the reflux ratio and throughput is performed byappropriately controlling the temperature and pressure for the reaction.The appropriate control of the reflux ratio and throughput is extremelyadvantageous in that the polymerization reaction can be completed in arelatively short time, thereby improving not only the productivity ofthe copolycarbonate diol but also the quality thereof.

The reaction temperature in the step (1) is generally in the range offrom 125 to 160° C., preferably from 130 to 150° C.

When the reaction temperature is lower than 125° C., the rate of thetransesterification reaction becomes low and hence the reaction timebecomes long.

On the other hand, when the reaction temperature is higher than 160° C.,the diol (I) (1,3-propanediol) bonded to the terminals of thecopolycarbonate prepolymer is likely to get easily eliminated as atrimethylene carbonate, thus rendering it difficult to satisfactorilyincrease the molecular weight of the obtained copolycarbonateprepolymer.

Further, when the reaction temperature is higher than 160° C., thefollowing disadvantage also occurs. In the case where ethylene carbonateis used as the carbonate compound (III), when the reaction temperatureis higher than 160° C., the ethylene carbonate undergoes adecarboxylation, thus converting the ethylene carbonate into an ethyleneoxide. The formed ethylene oxide reacts with the terminal hydroxylgroups of the diol (I) or (II), thus producing a diol containing anether linkage. The formed ether linkage-containing diol gets polymerizedin substantially the same manner as the diols (I) and (II), thusproducing a copolycarbonate prepolymer containing an ether linkage. Whenthis prepolymer is subjected to the step (2) described below, acopolycarbonate diol containing an ether linkage is obtained. Athermoplastic polyurethane obtained using such copolycarbonate diolexhibits poor resistance to heat and light.

In addition, in the case where 1,4-butanediol or 1,5-pentanediol is usedas the diol (II), when the reaction temperature is higher than 160° C.,there is a disadvantage in that a product formed by the reaction betweenthe diol (II) and ethylene carbonate, and/or the diol (II) bonded to theterminals of the copolycarbonate prepolymer produced in the reaction islikely to be easily eliminated as a cyclic ether (namely, atetrahydrofuran and/or a tetrahydropyran).

With respect to the pressure for the reaction, it is generally in therange of from atmospheric pressure to 0.5 kPa; however, due to thereason as mentioned above, it is preferred that the reaction isperformed under reduced pressure.

With respect to the timing of the termination of the polymerizationreaction, there is no particular limitation; however, when thepolymerization reaction is terminated at an early stage of reactionwhere the conversion of diol (as described below) is still low, there isa disadvantage in that not only does the yield of the obtainedcopolycarbonate prepolymer become low, but also the reaction time of thestep (2) as described below becomes long.

On the other hand, when the polymerization reaction is performed so asto achieve a very high conversion of diol, there is a problem in that,as the reaction proceeds, the diols (I) and (II) and the carbonatecompound (III) contained in the reaction mixture in the reactor areconsumed and hence the concentrations of the diols (I) and (II) and thecarbonate compound (III) in the reaction mixture become low, thusdecreasing the polymerization rate. As a result, an extremely longperiod of time is required for achieving a very high conversion of diol.

Therefore, it is generally preferred that the polymerization reaction inthe step (1) is terminated when the conversion of diol has reached 50 to95%. The conversion of diol is represented by the following formula:Conversion of diol (%)={1−(A/B)}×100

-   -   wherein:    -   A is the total molar amount of diols (I) and (II) contained in        the reaction mixture; and    -   B is the total molar amount of diols (I) and (II) charged into        the reactor.

The value of A as mentioned above is obtained by a method in which thereaction mixture obtained in the step (1) is subjected to gaschromatography (GC) analysis so as to determine the amounts (in mole) of1,3-propanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol, andthe value of A is calculated from the determined amounts of these diols.If desired, before being subjected to the GC analysis, the reactionmixture may be appropriately diluted with an organic solvent, such asacetone and the like.

The conditions for the GC analysis are as follows.

-   Apparatus: GC-14B (manufactured and sold by Shimadzu Corporation,    Japan)-   Column: DB-WAX (manufactured and sold by J & W, U.S.A.)-   (column length: 30 m, film thickness: 0.25 μm)-   Detector: FID (flame ionization detector)-   Internal standard: diethylene glycol diethyl ether-   Temperature: the temperature was first maintained at 60° C. for 5    minutes and then elevated to 250° C. at a rate of 10° C./min.

The copolycarbonate prepolymer obtained in the step (1) generallyexhibits a degree of polymerization in the range of from 2 to 10.Generally, the degree of polymerization of the copolycarbonateprepolymer is controlled by adjusting the amount of the hydroxylgroup-containing by-product removed from the reaction system.

Hereinbelow, an explanation is made of the step (2) of the process forproducing the copolycarbonate diol of the present invention.

In the step (2), the copolycarbonate prepolymer obtained in the step (1)is subjected to a self-condensation reaction, thereby producing thecopolycarbonate diol of the present invention. Since thisself-condensation reaction is a transesterification, as the reactionproceeds, the diols (I) and (II) are eliminated from the terminals ofthe copolycarbonate diol being produced. Since the transesterificationreaction is an equilibrium reaction, when the diols (I) and (II)accumulate in the reaction system, the polymerization does notsatisfactorily advance. Therefore, it is preferred that thepolymerization reaction is performed while removing the eliminated diols(I) and (II) from the reaction system.

Generally, the removal of the eliminated diols (I) and (II) from thereaction system is performed by evaporation and hence, in the step (2),the polymerization reaction is generally performed under reducedpressure.

Specifically, the step (2) is generally performed as follows.

The contents (reaction mixture) of the reactor are heated under reducedpressure to effect a self-condensation reaction while removing to theoutside of the reaction system a vapor being generated which iscomprised mainly of the eliminated diols (I) and (II). Differing fromthe case of the step (1), in the step (2), for efficiently removing thediols (I) and (II) as they are eliminated from the copolycarbonate diolbeing produced, it is preferred that the vapor comprised mainly of theeliminated diols (I) and (II) is directly removed from the reactionsystem to the outside, without using a fractionating column or the like.In addition, it is preferred that, by using a thin film evaporator, thereaction mixture obtained in the step (1) is caused to flow down in theform of a thin film in the evaporator, thereby evaporating off theeliminated diols (I) and (II) while performing the reaction in the step(2).

In the step (2), generally, the reaction mixture obtained in the step(1), as such, namely without being purified, is subjected to aself-condensation reaction. The reaction mixture may contain unreacteddiols (I) and (II) or unreacted carbonate compound (III); however, theseunreacted substances are removed either in the depressurizationoperation immediately upon initiation of the reaction in the step (2) orat the early stage of the reaction in the step (2).

In the step (2), the reaction temperature is generally in the range offrom 125 to 170° C., preferably from 130 to 150° C.

The diols (I) and (II) and the carbonate compound (III) used as the rawmaterials in the step (1), may cause a side reaction under hightemperature conditions, thus forming an ether compound whichdeteriorates the properties of the thermoplastic polyurethane producedusing the obtained copolycarbonate diol. In the step (2), however, thereaction is performed under conditions wherein the diols (I) and (II)and the carbonate compound (III) are present only in small amounts inthe reaction system; in addition, as the reaction proceeds, the amountsof the diols (I), (II) and the carbonate compound (III) becomesubstantially zero. Hence, an ether compound is formed only in a verysmall amount in the step (2). Therefore, in the step (2), the reactiontemperature can be higher than in the step (1).

However, when the reaction temperature is higher than 170° C., thedecomposition (i.e., depolymerization) of the obtained copolycarbonatediol is likely to occur, leading to a problem in that a copolycarbonatediol having the desired composition and molecular weight cannot beobtained.

On the other hand, when the reaction temperature is lower than 125° C.,the reaction rate is low and hence the reaction time becomes long.

With respect to the pressure (namely, the degree of vacuum) for thereaction in the step (2), it is generally in the range of from 0.10 to10 kPa. For saving the reaction time, it is preferred that the pressureis in the range of from 0.2 to 2 kPa.

The lower the pressure for the reaction (namely, the higher the degreeof vacuum), the higher the facility in removal of eliminated diols (I)and (II) from the reaction system, and hence the higher the rate of thereaction. However, for increasing the degree of vacuum, use of a higherperformance vacuum pump is required. Use of such vacuum pump posesproblems in that such vacuum pump is not easily available, and that,even when such vacuum pump is available, the equipment cost becomeshigh.

If desired, the polymerization reaction and the self-condensationreaction can be performed in the presence of a catalyst. The catalystcan be appropriately selected from the catalysts conventionally used fora transesterification.

Examples of such catalysts include metals, such as lithium, sodium,potassium, rubidium, cesium, magnesium, calcium, strontium, barium,zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony,arsenic and cerium, and compounds thereof. Examples of metal compoundsinclude salts, alkoxides and organometal compounds. Among these,especially preferred are titanium compounds, such as titaniumtetrabutoxide, titanium tetra-n-propoxide and titaniumtetra-isopropoxide; tin compounds, such as dibutyltin oxide, tinoxalate, dibutyltin dimaleate and dibutyltin dilaurate; and leadcompounds, such as tetraphenyllead, lead acetate and lead stearate.

The amount of catalyst is generally in the range of from 0.00001 to 1%by weight, based on the total weight of the raw materials charged intothe reactor.

In the case where the copolycarbonate diol of the present invention isused as a material for producing a thermoplastic elastomer, especially apolyester polycarbonate elastomer, when a residue of the catalyst ispresent in the copolycarbonate diol, there is a problem in that atransesterification occurs between the hard segment (i.e., polyester),and the soft segment (i.e., polycarbonate diol) due to the presence ofthe residual catalyst, leading to a deterioration of the properties ofthe thermoplastic elastomer obtained. For preventing the occurrence ofsuch problem, it is preferred that the polymerization is performedwithout using a catalyst. On the other hand, when the polymerization isperformed in the presence of a catalyst, it is required that, prior tothe use of the copolycarbonate diol as a material for producing athermoplastic elastomer, the copolycarbonate diol be purified so as toremove the residual catalyst and to prevent the occurrence of thedeterioration of the properties of the thermoplastic elastomer derivedtherefrom. From the viewpoint of reducing the work load of thepurification operation, when the polymerization reaction is performed inthe presence of a catalyst, it is preferred that the catalyst is used inan amount in the range of from 0.00001 to 0.0001% by weight, based onthe total weight of the raw materials charged into the reactor.

The thus obtained copolycarbonate diol of the present invention and apolyisocyanate are subjected to copolymerization, to thereby obtain thethermoplastic polyurethane of the present invention. The thermoplasticpolyurethane of the present invention exhibits excellent properties withrespect to flexibility, heat resistance, low temperature properties,weathering resistance, strength, and molding processability. Therefore,the thermoplastic polyurethane of the present invention is extremelyuseful as a material for producing various shaped articles. Hereinbelow,an explanation is made of the thermoplastic polyurethane of the presentinvention.

Examples of polyisocyanates used for producing the thermoplasticpolyurethane of the present invention include conventional aromaticdiisocyanates, such as 2,4-tolylene diisocyanate, 2,6-tolylenediisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylenediisocyanate (TDI), diphenylmethane-4,4′-diisocyanate (MDI),naphthalene-1,5-diisocyanate (NDI), 3,3′-dimethyl-4,4′-biphenylenediisocyanate, crude TDI, polymethylenepolyphenyl isocyanate, crude MDI,xylylene diisocyanate (XDI) and phenylene diisocyanate; conventionalaliphatic diisocyanates, such as 4,4′-methylenebiscyclohexyldiisocyanate (hydrogenated MDI), hexamethylene diisocyanate (HMDI),isophorone diisocyanate (IPDI) and cyclohexane diisocyanate(hydrogenated XDI); and modified products thereof, such as isocyanurateproducts, carbodimide products and biuret products.

In the present invention, if desired, a chain extender may be used as acopolymerizable component. As the chain extender, there may be employeda customary chain extender used for producing a polyurethane, asdescribed in, for example, “Saishin Poriuretan Oyo-Gijutsu (LatestApplication Techniques of Polyurethane)” edited by Keiji Iwata, pp.25-27, CMC, Japan, 1985. Examples of chain extenders include water, alow molecular weight polyol, a polyamine and the like. Depending on theuse of the thermoplastic polyurethane, if desired, a conventional highmolecular weight polyol may also be used in combination with thecopolycarbonate diol of the present invention as long as the propertiesof the produced polyurethane are not adversely affected. As theconventional high molecular weight polyol, there may be employed thosewhich are described in, for example, pp. 12-23 of “Poriuretan Foumu(Polyurethane Foam)” by Yoshio Imai, published by Kobunshi Kankokai,Japan, 1987. Examples of high molecular weight polyols include apolyester polyol and a polyether carbonate having a polyoxyalkylenechain (i.e., a polyether carbonate polyol).

Specifically, a low molecular weight polyol used as a chain extender isgenerally a diol monomer having a molecular weight of not more than 300.Examples of such low molecular weight polyols include aliphatic diols,such as ethylene glycol, 1,3-propanediol, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, neopentyl glycol and 1,10-decanediol.

Further examples of low molecular weight polyols used as a chainextender include alicyclic diols, such as 1,1-cyclohexanedimethanol,1,4-cyclohexanedimethanol and tricyclodecanedimethanol; xylylene glycol,bis(p-hydroxy)diphenyl, bis(p-hydroxyphenyl)propane,2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, bis[4(2-hydroxy)phenyl]sulfone and 1,1-bis[4-(2-hydroxyethoxy)phenyl] cyclohexane. As achain extender, ethylene glycol and 1,4-butanediol are preferred.

For producing the thermoplastic polyurethane of the present invention, aurethane-forming technique known in the art may be employed. Forexample, the copolycarbonate diol of the present invention is reactedwith an organic polyisocyanate under atmospheric pressure at atemperature of from room temperature to 200° C. to form a thermoplasticpolyurethane. When a chain extender is optionally used, a chain extendermay be added to the reaction system either before initiating thereaction or during the reaction. For a specific method for producing athermoplastic polyurethane, reference can be made to U.S. Pat. No.5,070,173.

In the polyurethane-forming reaction, a conventional polymerizationcatalyst, such as a tertiary amine and an organic salt of a metal, e.g.,tin or titanium, may be employed (see, for example, “Poriuretan Jushi(Polyurethane Resin)” written by Keiji Iwata, pages 23 to 32, publishedin 1969 by The Nikkan Kogyo Shimbun, Ltd., Japan). Thepolyurethane-forming reaction may be performed in a solvent. Preferredexamples of solvents include dimethylformamide, diethylformamide,dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, methyl isobutylketone, dioxane, cyclohexanone, benzene, toluene and ethyl cellosolve.

In the polyurethane-forming reaction, a compound having only one activehydrogen atom which is capable of reacting with an isocyanate group, forexample, a monohydric alcohol, such as ethyl alcohol or propyl alcohol,and a secondary amine, such as diethylamine or di-n-propylamine, may beused as a reaction terminator.

In the present invention, it is preferred that stabilizers, such as heatstabilizers (for example, antioxidants) and light stabilizers, are addedto the thermoplastic polyurethane.

Examples of antioxidants (heat stabilizers) include aliphatic, aromaticor alkyl-substituted aromatic esters of phosphoric acid or phosphorousacid; hypophosphinic acid derivatives; phosphorus-containing compounds,such as phenylphosphonic acid, phenylphosphinic acid, diphenylphosphonicacid, polyphosphonate, dialkylpentaerythritol diphosphite and adialkylbisphenol A diphosphite; phenol derivatives, especially, hinderedphenol compounds; sulfur-containing compounds, such as thioether typecompounds, dithioacid salt type compounds, mercaptobenzimidazole typecompounds, thiocarbanilide type compounds and thiodipropionic acidesters; and tin-containing compounds, such as tin malate and dibutyltinmonooxide.

In general, antioxidants can be classified into primary, secondary andtertiary antioxidants. As hindered phenol compounds used as a primaryantioxidant, Irganox 1010 (trade name) (manufactured and sold byCIBA-GEIGY, Switzerland) and Irganox 1520 (trade name) (manufactured andsold by CIBA-GEIGY, Switzerland) are preferred. As phosphorus-containingcompounds used as a secondary antioxidant, PEP-36, PEP-24G and HP-10(each being a trade name) (each manufactured and sold by ASAHI DENKAK.K., Japan) and Irgafos 168 (trade name) (manufactured and sold byCIBA-GEIGY, Switzerland) are preferred. Further, as sulfur-containingcompounds used as a tertiary antioxidant, thioether compounds, such asdilaurylthiopropionate (DLTP) and distearylthiopropionate (DSTP) arepreferred.

Examples of light stabilizers include UV absorber type light stabilizersand radical scavenger type light stabilizers. Specific examples of UVabsorber type light stabilizers include benzotriazole compounds andbenzophenone compounds. Specific examples of radical scavenger typelight stabilizers include hindered amine compounds.

The above-exemplified stabilizers can be used individually or incombination. The stabilizers are added to the thermoplastic polyurethanein an amount of from 0.01 to 5 parts by weight, preferably from 0.1 to 3parts by weight, more preferably from 0.2 to 2 parts by weight, relativeto 100 parts by weight of the thermoplastic polyurethane.

If desired, a plasticizer may be added to the thermoplastic polyurethaneof the present invention. Examples of plasticizers include phthalicesters, such as dioctyl phthalate, dibutyl phthalate, diethyl phthalate,butylbenzyl phthalate, di-2-ethylhexyl phthalate, diisodecyl phthalate,diundecyl phthalate and diisononyl phthalate; phosphoric esters, such astricresyl phosphate, triethyl phosphate, tributyl phosphate,tri-2-ethylhexyl phosphate, trimethylhexyl phosphate, tris-chloroethylphosphate and tris-dichloropropyl phosphate; aliphatic esters, such asoctyl trimellitate, isodecyl trimellitate, trimellitic esters,dipentaerythritol esters, dioctyl adipate, dimethyl adipate,di-2-ethylhexyl azelate, dioctyl azelate, dioctyl sebacate,di-2-ethylhexyl sebacate and methylacetyl ricinoleate; pyromelliticesters, such as octyl pyromellitate; epoxy plasticizers, such asepoxidized soyabean oil, epoxidized linseed oil and epoxidized fattyacid alkyl esters; polyether plasticizers, such as adipic ether esterand polyether; liquid rubbers, such as liquid NBR, liquid acrylic rubberand liquid polybutadiene; and non-aromatic paraffin oil.

The above-exemplified plasticizers may be used individually or incombination. The amount of the plasticizer added to the thermoplasticpolyurethane is appropriately chosen in accordance with the requiredhardness and properties of the thermoplastic polyurethane; however, ingeneral, it is preferred that the plasticizer is used in an amount offrom 0.1 to 50 parts by weight, relative to 100 parts by weight of thethermoplastic polyurethane.

In addition, other additives, such as inorganic fillers, lubricants,colorants, silicon oil, foaming agents, flame retardants and the like,may be added to the thermoplastic polyurethane of the present invention.Examples of inorganic fillers include calcium carbonate, talc, magnesiumhydroxide, mica, barium sulfate, silicic acid (white carbon), titaniumoxide and carbon black. These additives may be added to thethermoplastic polyurethane of the present invention in an amount whichis generally used for the conventional thermoplastic polyurethane.

The Shore D hardness of the thermoplastic polyurethane of the presentinvention is preferably in the range of from 20 to 70, more preferablyfrom 25 to 50. When the Shore D hardness is less than 20, heat stabilityand scratch resistance become low. On the other hand, when the Shore Dhardness is more than 70, low temperature properties and softness becomeunsatisfactory.

Further, the melt flow rate (as measured at 230° C. under a load of 2.16kg; hereinafter, abbreviated to “MFR”) of the thermoplastic polyurethaneof the present invention is preferably from 0.5 to 100 g/10 minutes,more preferably from 5 to 50 g/10 minutes, still more preferably from 10to 30 g/10 minutes. When MFR is less than 0.5 g/10 minutes, theinjection moldability of the thermoplastic polyurethane becomes poor andthe injection molding is likely to result in “incomplete filling” (thatis, the filling of the mold cavity becomes incomplete). On the otherhand, when MFR is more than 100 g/10 minutes, not only the mechanicalproperties (such as tensile strength and elongation at break) andabrasion resistance, but also low temperature properties are lowered.

With respect to the molecular weight of the thermoplastic polyurethaneof the present invention, it is preferred that each of the numberaverage molecular weight (Mn) and weight average molecular weight (Mw)of the thermoplastic polyurethane is in the range of from 10,000 to200,000. Each of Mn and Mw is measured by GPC analysis, using acalibration curve obtained with respect to standard polystyrene samples.

The thus obtained thermoplastic polyurethane of the present inventionexhibits excellent properties with respect to flexibility, heatresistance, low temperature properties, weathering resistance, strength,and molding processability. Therefore, the thermoplastic polyurethane ofthe present invention is extremely useful as a material for producingvarious shaped articles, such as automobile parts, parts for householdelectric appliances, toys and sundry goods. Especially, thethermoplastic polyurethane of the present invention is useful forproducing shaped articles which are required to have high strength, suchas hoses, sheets and industrial belts; and shaped articles which arerequired to have high flexibility, such as interior and exterior partsfor automobiles (for example, window moles, bumpers, skin parts for aninstrument panel, and grips), spandexes, bands for wristwatches, andshoe soles.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, the present invention will be described in more detail withreference to the following Examples and Comparative Examples; however,they should not be construed as limiting the scope of the presentinvention.

In the following Examples and Comparative Examples, various measurementsand analyses were performed by the following methods.

(1) Number Average Molecular Weight (Mn) of Polycarbonate Diol

The acid values of the polycarbonate diols obtained in Examples andComparative Examples were measured (wherein the acid value is defined asthe amount (mg) of potassium hydroxide (KOH) required for neutralizingthe acidic groups in 1 g of a polycarbonate diol). As a result, it wasfound that none of the polycarbonate diols had an acid value exceeding0.01.

The polycarbonate diols were examined by ¹³C-NMR spectroscopy (nuclearmagnetic resonance measurement apparatus: α-400; manufactured and soldby JEOL LTD., Japan) (observation frequency: 100 MHz, accumulationnumber: 10,000, and measuring temperature: 20° C.). In the ¹³C-NMRspectra of the polycarbonate diols, no signal ascribed to an acid group,such as a carboxyl group, was observed.

From the results of the measurements, it was found that thepolycarbonate diols contained substantially no acid groups, that is,substantially all terminal groups of the polycarbonate diols werehydroxyl groups.

Thus, it was found that the number average molecular weights (Mn) of thepolycarbonate diols were able to be calculated from the hydroxyl valuesof the polycarbonate diols (wherein the hydroxyl value can be measuredby the method as shown in item (2) below). Therefore, the number averagemolecular weight (Mn) of each polycarbonate diol was calculated from thehydroxyl value (mg−KOH/g) thereof in accordance with the followingformula:Mn=(2×56.11×1,000)÷hydroxyl value(2) Hydroxyl Value of Polycarbonate Diol

An acetylation reagent was prepared by adding pyridine to 12.5 g ofacetic anhydride so that the total volume became 50 ml.

2.5 to 5.0 g of a polycarbonate diol obtained was precisely weighed outand placed in a 100 ml eggplant-shaped flask. 5 ml of the acetylationreagent prepared above and 10 ml of toluene were put into theeggplant-shaped flask by means of a transfer pipette, and the resultantmixture in the eggplant-shaped flask was then heated at 100° C. for 1hour while stirring to thereby obtain a reaction mixture.

2.5 ml of distilled water was put into the eggplant-shaped flaskcontaining the obtained reaction mixture by means of a transfer pipette,and the resultant mixture in the eggplant-shaped flask was furtherstirred for 10 minutes, followed by cooling for a few minutes. 12.5 mlof ethanol and a few drops of a phenolphthalein solution as an indicatorwere added to the mixture in the eggplant-shaped flask to obtain asolution. The obtained solution was titrated with a 0.5 mol/l potassiumhydroxide solution in ethanol.

On the other hand, a blank test was performed by repeating substantiallythe same procedure as mentioned above, except that a polycarbonate diolwas not used.

Then, based on the results of these operations, the hydroxyl value ofthe polycarbonate diol was calculated in accordance with the followingformula:Hydroxyl value (mg−KOH/g)=((B−A)×28.5×f)/Cwherein:

-   -   A represents the amount (ml) of the ethanol solution of        potassium hydroxide used for the titration;    -   B represents the amount (ml) of the ethanol solution of        potassium hydroxide used for the titration performed in the        blank test;    -   C represents the weight (g) of the polycarbonate diol; and    -   f represents the factor of the ethanol solution of potassium        hydroxide.

Hereinafter, the hydroxyl value is referred to as the “OH value”.

(3) Composition of the Recurring Units of Polycarbonate Diol

1 g of a copolycarbonate diol was weighed out and placed in a 100 mleggplant-shaped flask. 30 g of ethanol and 4 g of potassium hydroxidewere added to the copolycarbonate diol in the eggplant-shaped flask, anda reaction was performed at 100° C. for 1 hour, thereby obtaining areaction mixture.

The obtained reaction mixture was cooled to room temperature, and a fewdrops of a phenolphthalein solution as an indicator were added to thereaction mixture, followed by neutralization using hydrochloric acid, toobtain a mixture. The obtained mixture was cooled in a refrigerator for1 hour to thereby precipitate a salt (potassium chloride) formed byneutralization. The precipitated potassium chloride was removed byfiltration and the resultant filtrate was analyzed by gas chromatographyto thereby determine the amounts (mol) of 1,3-propanediol,1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol which were containedin the filtrate.

The composition of recurring units was evaluated as the ratio (mol %) ofrecurring units derived from 1,3-propanediol, based on the total molaramount of recurring units derived from the above-mentioned diols. Thecomposition of recurring units of the polycarbonate diol was calculatedin accordance with the following formula:Composition of recurring units (mol %)=(D/E)×100wherein:

-   -   D represents the molar amount of 1,3-propanediol; and    -   E represents the total molar amount of the above-mentioned        diols.

With respect to the copolycarbonate diol obtained in Comparative Example3 (wherein the copolycarbonate diol contained no recurring units derivedfrom 1,3-propanediol), the composition of recurring units was evaluatedas the ratio (mol %) of recurring units derived from 1,5-pentanediol,based on the total molar amount of recurring units derived from1,5-pentanediol and 1,6-hexanediol. That is, the composition ofrecurring units of the copolycarbonate diol obtained in ComparativeExample 3 was determined in substantially the same manner as mentionedabove, except that, in the above-mentioned formula, D represents themolar amount of 1,5-pentanediol and E represents the total molar amountof 1,5-pentanediol and 1,6-hexanediol.

Conditions for gas chromatography were as follows.

Apparatus: GC-14B (manufactured and sold by Shimadzu Corporation, Japan)Column: DB-WAX (manufactured and sold by J & W, U.S.A.) (column length:30 m; film thickness: 0.25 μm) Detector: FID (flame ionization detector)Internal standard: diethylene glycol diethyl ether Temperature: thetemperature was first maintained at 60° C. for 5 minutes and thenelevated to 250° C. at a rate of 10° C./min.(4) Viscosity of Polycarbonate Diol

The viscosity was measured at 50° C. in accordance with ASTM, D1986,p.193 to 194, using the digital Brookfield viscometer LVTDV-1(manufactured and sold by BROOKFIELD ENGINEERING LABORATORIES INC.,U.S.A.) (wherein the spindle (rotor) No. 34 was used).

(5) Melting Temperature (Tm) and Glass Transition Temperature (Tg) ofPolycarbonate Diol

About 10 mg of a polycarbonate diol was precisely weighed out and placedin an aluminum pan and subjected to measurement using a differentialscanning calorimeter, in order to determine the melting temperature andglass transition temperature of the polycarbonate diol under thefollowing analysis conditions:

Apparatus: DSC220C (manufactured and sold by Seiko Instruments Inc,Japan) Temperature range of measurement: −120 to 70° C. Temperatureelevation rate: 10° C./min.(6) Number Average Molecular Weight and Weight Average Molecular Weightof Thermoplastic Polyurethane

The number average molecular weight and weight average molecular weightof a thermoplastic polyurethane were measured by gel permeationchromatography (GPC) using a calibration curve obtained with respect tostandard monodisperse polystyrene samples.

(7) Various Mechanical Properties of Thermoplastic Polyurethane

Measurements were performed as follows.

(i) Shore ‘D’ Hardness [−]:

Shore ‘D’ hardness was measured in accordance with ASTM D2240, D type,at 23° C.

(ii) Tensile Stress [kgf/cm²]:

Tensile stress was measured in accordance with JIS K6251 (using adumbbell No. 3 prescribed therein). A pressed sheet having a thicknessof 2 mm was used as a test sample.

(iii) Tensile Strength at 100% Elongation [kgf/cm²]:

Tensile strength was measured in accordance with JIS K6251 (using adumbbell No. 3 prescribed therein). A pressed sheet having a thicknessof 2 mm was used as a test sample.

(iv) Elongation [%]:

Elongation was measured in accordance with JIS K6251 (using a dumbbellNo. 3 prescribed therein). A pressed sheet having a thickness of 2 mmwas used as a test sample.

(v) Impact Resilience [%]:

Impact resilience was measured in accordance with JIS K6255 (using aLübke pendulum, 23° C.).

EXAMPLE 1

305 g of 1,3-propanediol, 355 g of 1,6-hexanediol and 760 g of ethylenecarbonate were charged into a 2-liter separable flask equipped with astirrer, a thermometer and an Oldershaw distillation column having avacuum jacket and having a reflux head at the top thereof. The resultantmixture in the separable flask was stirred at 70° C. to obtain asolution. To the obtained solution was added 0.015 g of lead acetatetrihydrate as a catalyst, to obtain a mixture.

The flask was connected to a vacuum pump, and the mixture in the flaskwas subjected to a polymerization reaction for 12 hours while stirringunder conditions wherein the degree of vacuum was from 1.0 to 1.5 kPaand the internal temperature of the flask was 140° C. (wherein the flaskwas heated in an oil bath having a temperature of 175° C.), to obtain areaction mixture. During the reaction, a portion of the distillate waswithdrawn through the reflux head so that the reflux ratio became 4.

Then, the Oldershaw distillation column was removed from the separableflask, and a condenser and a receiver were attached to the separableflask to thereby form a vacuum distillation apparatus. Under a vacuum of0.5 kPa, the separable flask was heated in an oil bath (the bathtemperature: 180° C.) so that the internal temperature of the separableflask was elevated to a temperature in the range of from 140 to 150° C.,to thereby distill off 1,3-propanediol, 1,6-hexanediol, ethylene glycol(which was derived from ethylene carbonate) and ethylene carbonate whichwere contained in the reaction mixture in the flask.

Thereafter, the temperature of the oil bath was elevated to 185° C.while maintaining the degree of vacuum in the flask at 0.5 kPa, therebyelevating the internal temperature of the separable flask to atemperature in the range of from 160 to 165° C., and the heating wascontinued for 4 hours to effect a reaction while distilling off1,3-propanediol and 1,6-hexanediol which were by-produced during thereaction.

As a result, 721 g of a copolycarbonate diol was obtained. The obtainedcopolycarbonate diol is hereinafter referred to as “pc-a”. Thecopolycarbonate diol pc-a was a viscous liquid at room temperature.

The properties of pc-a, i.e., OH value, number average molecular weight,recurring unit composition (composition, mol %), melting temperature,glass transition temperature and viscosity, are shown in Table 1.

EXAMPLE 2

228 g of 1,3-propanediol, 270 g of 1,4-butanediol and 530 g of ethylenecarbonate were charged into a 2-liter separable flask equipped with astirrer, a thermometer and an Oldershaw distillation column having avacuum jacket and having a reflux head at the top thereof. The resultantmixture in the separable flask was stirred at 70° C. to obtain asolution. To the obtained solution was added 0.014 g of lead acetatetrihydrate as a catalyst, to obtain a mixture.

The flask was connected to a vacuum pump, and the mixture in the flaskwas subjected to a polymerization reaction for 20 hours while stirringunder conditions wherein the degree of vacuum was from 1.0 to 1.5 kPaand the internal temperature of the flask was 130° C. (wherein the flaskwas heated in an oil bath having a temperature of 170° C.), to obtain areaction mixture. During the reaction, a portion of the distillate waswithdrawn through the reflux head so that the reflux ratio became 4.

Then, the Oldershaw distillation column was removed from the separableflask, and a condenser and a receiver were attached to the separableflask to thereby form a vacuum distillation apparatus. Under a vacuum of0.5 kPa, the separable flask was heated for 4 hours in an oil bath (thebath temperature: 170° C.) so that the internal temperature of theseparable flask was maintained at a temperature in the range of from 130to 140° C., to thereby effect a reaction. During the reaction,1,3-propanediol, 1,4-butanediol, ethylene glycol (which was derived fromethylene carbonate) and ethylene carbonate which were contained in thereaction mixture in the flask, were distilled off.

As a result, 514 g of a copolycarbonate diol was obtained. The obtainedcopolycarbonate diol is hereinafter referred to as “pc-b”. Thecopolycarbonate diol pc-b was a viscous liquid at room temperature.

The properties of pc-b, i.e., OH value, number average molecular weight,recurring unit composition (composition, mol %), melting temperature,glass transition temperature and viscosity, are shown in Table 1.

COMPARATIVE EXAMPLE 1

Substantially the same procedure as in Example 1 was repeated exceptthat the amounts of 1,3-propanediol, ethylene carbonate and lead acetatetrihydrate were changed to 420 g, 440 g and 0.010 g, respectively, andthat 1,6-hexanediol was not used, to thereby obtain 364 g of apolycarbonate diol. Hereinafter, the thus produced polycarbonate diol isreferred to as “pc-c”. The polycarbonate diol pc-c was a viscous liquidat room temperature.

The properties of pc-c, i.e., OH value, number average molecular weight,recurring unit composition (composition, mol %), melting temperature,glass transition temperature and viscosity, are shown in Table 1.

COMPARATIVE EXAMPLE 2

472 g of 1,6-hexanediol and 344 g of ethylene carbonate were chargedinto a 2-liter separable flask equipped with a stirrer, a thermometerand an Oldershaw distillation column having a vacuum jacket and having areflux head at the top thereof. The resultant mixture in the separableflask was stirred at 70° C. to obtain a solution. To the obtainedsolution was added 0.010 g of lead acetate trihydrate as a catalyst, toobtain a mixture.

The flask was connected to a vacuum pump, and the mixture in the flaskwas subjected to a polymerization reaction for 8 hours while stirringunder conditions wherein the degree of vacuum was from 3.0 to 4.2 kPaand the internal temperature of the flask was 160° C. (wherein the flaskwas heated in an oil bath having a temperature of 190° C.), to obtain areaction mixture. During the reaction, a portion of the distillate waswithdrawn through the reflux head so that the reflux ratio became 4.

Then, the Oldershaw distillation column was removed from the separableflask, and a condenser and a receiver were attached to the separableflask to thereby form a vacuum distillation apparatus. Under a vacuum of0.5 kPa, the separable flask was heated in an oil bath (the bathtemperature: 190° C.) so that the internal temperature of the separableflask was elevated to a temperature in the range of from 160 to 170° C.,to thereby distill off unreacted diols and ethylene carbonate which werecontained in the reaction mixture in the flask.

Thereafter, the temperature of the oil bath was elevated to 200° C.while maintaining the degree of vacuum in the flask at 0.5 kPa, therebyelevating the internal temperature of the separable flask to atemperature in the range of from 170 to 190° C., and the heating wascontinued for 3 hours to effect a reaction while distilling off a diolwhich was formed during the reaction.

As a result, 457 g of a polycarbonate diol was obtained. The obtainedpolycarbonate diol is hereinafter referred to as “pc-d”. Thepolycarbonate diol pc-d was a white solid at room temperature.

The properties of pc-d, i.e., OH value, number average molecular weight,recurring unit composition (composition, mol %), melting temperature,glass transition temperature and viscosity, are shown in Table 1.

COMPARATIVE EXAMPLE 3

Substantially the same procedure as in Comparative Example 2 wasrepeated except that the amounts of 1,6-hexanediol, ethylene carbonateand lead acetate trihydrate were changed to 325 g, 485 g and 0.015 g,respectively, and that 285 g of 1,5-pentanediol was used, to therebyobtain 385 g of a copolycarbonate diol. Hereinafter, the thus producedcopolycarbonate diol is referred to as “pc-e”. The copolycarbonate diolpc-e was a viscous liquid at room temperature.

The properties of pc-e, i.e., OH value, number average molecular weight,recurring unit composition (composition, mol %), melting temperature,glass transition temperature and viscosity, are shown in Table 1.

TABLE 1 Melting Glass tran- Compo- temper- sition tem- Vis- Abbre- OHsition ature- perature cosity via- value Mn (mol %) (° C.) (° C.) (cp)tion Ex. 1 61 1840 36 — −53 5340 pc-a Ex. 2 69 1630 34 — −54 4890 pc-bComp. 186 600 100  — −54 887 pc-c Ex. 1 Comp. 52 2160 — 41 −51 15200pc-d Ex. 2 Comp. 56 2000  49¹⁾ — −54 7400 pc-e Ex. 3 ¹⁾The ratio (mol %)of recurring units derived from 1,5-pentanediol, based on the totalmolar amount of recurring units derived from 1,5-pentanediol and1,6-hexanediol.

EXAMPLE 3

200 g of pc-a obtained in Example 1 and 80.3 g ofdiphenylmethane-4,4′-diisocyanate (MDI) were charged into a reactionvessel equipped with a stirrer, a thermometer and a condenser. Areaction of the resultant mixture was performed at 100° C. for 4 hours,thereby obtaining a prepolymer having terminal NCO groups. To theobtained prepolymer were added 30 g of 1,4-butanediol as a chainextender and 0.006 g of dibutyltin dilaurylate as a catalyst. Theresultant mixture was reacted at 140° C. for 60 minutes in a universallaboratory scale extruder (Universal Laboratory Scale Extruder KR-35type; manufactured and sold by Kasamatsu Plastic Engineering andResearch Co., Ltd., Japan) equipped with a kneader, thereby obtaining athermoplastic polyurethane. The obtained thermoplastic polyurethane wasthen pelletized using the extruder.

The number average molecular weight (Mn) and weight average molecularweight (Mw) of the thermoplastic polyurethane were 73,000 and 126,000,respectively, as measured by GPC analysis, using a calibration curveobtained with respect to standard polystyrene samples. The properties ofthe thermoplastic polyurethane are shown in Table 2.

EXAMPLE 4

A thermoplastic polyurethane was produced in substantially the samemanner as in Example 3 except that pc-b obtained in Example 2 was usedas a copolycarbonate diol, instead of pc-a. The molecular weight andproperties of the thermoplastic polyurethane are shown in Table 2.

EXAMPLE 5

A thermoplastic polyurethane was produced in substantially the samemanner as in Example 3 except that the amounts of MDI and 1,4-butanediolwere changed to 24.5 g and 4.16 g, respectively. The molecular weightand properties of the thermoplastic polyurethane are shown in Table 2.

TABLE 2 Properties of polyurethane Ex. 3 Ex. 4 Ex. 5 Polycarbonate diolpc-a pc-b pc-a Number average molecular 7.3 6.9 6.6 weight (×10⁴ Mn)Weight average molecular 12.6 12.8 14.2 weight (×10⁴ Mw) PropertiesHardness (shore D) 43 44 26 100% tensile stress 36 38 26 (kgf/cm²)Tensile strength 180 200 130 (kgf/cm²) Elongation (%) 500 480 660 Impactresilience (%) 58 53 62

COMPARATIVE EXAMPLES 4, 5 and 6

Thermoplastic polyurethanes were individually produced in substantiallythe same manner as in Example 3 except that pc-c, pc-d and pc-e wereused in Comparative Examples 4, 5, and 6, respectively, instead of pc-a.The molecular weight and properties of each of the thermoplasticpolyurethanes are shown in Table 3.

TABLE 3 Comp. Comp. Comp. Ex. 4 Ex. 5 Ex. 6 Polycarbonate diol pc-c pc-dpc-e Number average molecular 7.1 7.5 6.9 weight (×10⁴ Mn) Weightaverage molecular 13.2 13.8 12.3 weight (×10⁴ Mw) Properties Hardness(shore D) 60 53 46 100% tensile stress 63 58 46 (kgf/cm²) Tensilestrength 220 210 200 (kgf/cm²) Elongation (%) 400 440 450 Impactresilience (%) 42 46 49

INDUSTRIAL APPLICABILITY

The copolycarbonate diol of the present invention is a liquid having lowviscosity. Therefore, the copolycarbonate diol of the present inventionis easy to handle, as compared to the conventional polycarbonate diolswhich are solids or highly viscous liquids. Hence, the copolycarbonatediol of the present invention is advantageous for various uses, such asa raw material for producing a thermoplastic elastomer (such as athermoplastic polyurethane) used for producing various shaped articles(for example, a spandex, which is a polyurethane elastomeric fiber); acomponent for a coating material or an adhesive; and a polymericplasticizer.

The thermoplastic polyurethane of the present invention exhibitsexcellent properties with respect to flexibility, heat resistance, lowtemperature properties, weathering resistance, strength, and moldingprocessability. Therefore, the thermoplastic polyurethane of the presentinvention is extremely useful as a material for producing various shapedarticles, such as automobile parts, parts for household electricappliances, toys and sundry goods. Especially, the thermoplasticpolyurethane of the present invention is useful for producing shapedarticles which are required to have high strength, such as hoses, sheetsand industrial belts; and shaped articles which are required to havehigh flexibility, such as interior and exterior parts for automobiles(for example, window moles, bumpers, skin parts for an instrument panel,and grips), spandexes, bands for wristwatches, and shoe soles.

1. A copolycarbonate diol comprising: (a) recurring units eachrepresented by the following formula (1):

(b) recurring units each independently represented by the followingformula (2):

wherein n is 4, 5 or 6; and (c) terminal hydroxyl groups, wherein saidcopolycarbonate diol has a number average molecular weight of from 300to 20,000, and wherein the amount of said recurring units (a) is from 10to 90% by mole, based on the total molar amount of said recurring units(a) and (b).
 2. The copolycarbonate did according to claim 1, which hasa number average molecular weight of from 500 to 10,000.
 3. Thecopolycarbonate diol according to claim 1 or 2, wherein the amount ofsaid recurring units (a) is from 20 to 80% by mole, based on the totalmolar amount of said recurring units (a) and (b).
 4. A thermoplasticpolyurethane obtained by copolymerizing the copolycarbonate diol claim 1with a polyisocyanate.